Re: Function Fit to 3D data set
- To: mathgroup at smc.vnet.net
- Subject: [mg57758] Re: Function Fit to 3D data set
- From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
- Date: Tue, 7 Jun 2005 05:59:47 -0400 (EDT)
- Organization: Uni Leipzig
- References: <d83eh8$o6e$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
a) use TriangularSufacePlot[] from
<<DiscreteMath`ComputationalGeometry`
TriangularSurfacePlot[data3D]
b)
points = {{1, 1, 1}, {1, 2, 4}, {1, 4, 16}}
f1 = FindFit[points,
a + b*x^0 * y^1 + c*x^0 *y^2 + k*x^2 *y^0 +
l*x^2 * y^1,
{a, b, c, k, l}, { x, y}]
work as expected.
Regards
Jens
"Adrienne R" <roehrich at unlserve.unl.edu> schrieb
im Newsbeitrag news:d83eh8$o6e$1 at smc.vnet.net...
>I have been trying to do several analyses with an
>[x,y,z] data set, where z is dependent on x and
>y. First, I tried a 3D plot. However, the only
>way I was able to get Mathematica to plot my data
>was to assume a grid form for x and y, and use
>ListPlot3D. First question: can Mathematica make
>a 3D plot from stated x,y,z points?
>
> Secondly, I am trying to fit a function to the
> data. I have determined a function to which to
> fit parameters. However, Mathematica does not
> seem to want to accept y as a variable. Here is
> a simple suggestion of what I was trying. Note,
> my function is much more complicated. Please
> also ignore if the given does not work as
> stated, as I'm making it up.
>
> points = {{1, 1, 1}, {1, 2, 4}, {1, 4, 16}}
> f1 = FindFit[points, a + b*x^0 * y^1 + c*x^0
> *y^2 +k*x^2 *y^0 + l*x^2 * y^1, {a, b, c, k, l},
> x, y]
>
> The error I receive is \!\(\*
> RowBox[{\(FindFit::"nonopt
> "\), \(\(:\)\(\ \)\), "\<\"Options expected (
> instead of \\!\\(y\\)) beyond
> position \\!\\(4\\) in
> \\!\\(\[LeftSkeleton] 1 \[RightSkeleton]\\). An
> \
> option must be a rule or a list of rules.
> \\!\\(\\*ButtonBox[\\\"Moreâ?¦\\\", \
> ButtonStyle->\\\"RefGuideLinkText\\\",
> ButtonFrame->None, \
> ButtonData:>\\\"General::nonopt\\\"]\\)\"\>"}]\)
>
> Second question: Can Mathematica take a set of
> x,y,z data where z is dependent on x and y and
> fit a function to it?
>
> Secondary question for both: How?
>
> Thanks for the help!
>